Bypassing and Authenticating a user login for a CI Pipeline profile where there is no instance of the login system

We have a web application we are testing. We have no issues when running test suites against our staging environments as the integrated application that controls the login and auth of users is present.

We start to come across issues when trying to run our test suite in our GitLab CI Pipeline profile because the other application where users are stored and login and authentication happens is not present in the pipeline instance/environment/setup. So our starting point login test cases don’t work as in the pipeline you go straight to the web application and not the other integrated system where users would usually login.

We are trying to find a way to mimic the login and auth step from the separate application that controls this for the CI Profile we have setup without that application being present in the pipeline setup.

Has anyone come across this scenario before and know of how we can achieve this?
Is it an API related thing or a Custom Keyword required set up as a variable against profiles that can be selected as a boolean true/false…?

The Katalon project is currently not setup in the root of the Gitlab repo but at a feature branch level folder.